Multiple chronic conditions (MCC) represent a substantial health problem for older adults in the United States. Increasing the coordination of care has been proposed by the Institute of Medicine as one promising approach for improving the quality of care for all patients, and particularly those with MCC. It is a key feature of many Affordable Care Act reforms such as patient-centered medical homes (MHs) and a central focus of the Community Care of North Carolina (CCNC) Medicaid medical home program. Both the burden of MCC and the need for care coordination are particularly notable within the older population with cancer, a growing demographic in the United States. MCC can complicate cancer treatment decisions and often are the leading cause of death for cancer survivors. The goal of this study is to investigate the management of MCC among cancer patients diagnosed after the age of 65 compared with cancer-free patients. This study will analyze complex older patients with diabetes, hyperlipidemia, and/or hypertension diagnosed with the four most common cancers (breast, colorectal, lung. and prostate) identified using two sources of linked cancer registry and administrative claims: the Surveillance, Epidemiology, and End Results program (SEER)-Medicare database and North Carolina Central Cancer Registry linked to Medicaid and Medicare claims. We will expand the horizon of analysis, relative to existing literature, to include management of MCC before the cancer diagnosis, during treatment, and into the survivorship phase. We hypothesize that medication adherence (Aim 1) will vary across phases of care and by cancer site relative to the non-cancer comparison group. The results of this study aim will identify cancer sites and phases of care in which additional support for care coordination and medication adherence may be crucial. We will also evaluate whether the level of care coordination modifies changes in adherence using claims-based measures of coordination (Aim 2) and enrollment in the CCNC medical home program (Aim 3). Our study will produce timely evidence of the effect of improved care coordination and MHs on medication adherence for older, complex cancer patients, including the nation's largest MH program.